The use of telescopes and binoculars to see far-away targets with clarity and precision is well known. In the case of long-range laser targeting, a common military practice, a soldier on the ground holds a laser beam on the desired target and a second soldier in a separate location, such as in an aircraft, shoots a laser-guided projectile in the general direction of the target. The projectile locks onto the laser “dot” on the target and thus is guided to remain on target all the way to impact. The challenge is to keep the laser “dot” from moving off the target, to keep the laser-guided projectile from missing the intended target and striking an unintended structure, object or person.
Viewing a far-away object is similar to striking a far-away target with a laser beam in that both involve light traveling over a distance to a rather precise spot. In the case of long-range image magnification (viewing a far-away object), the light originates at the “target” (the object to be viewed) and travels to the optics (e.g., the viewer's eyepiece), whereas with laser targeting, the light originates at the user's laser pointer device and travels to the target. It should be noted here that the adjective “telescopic” and the noun “scope” will be used to describe image viewing when the viewed object as seen through the scope appears closer than it actually is. “Observer,” “sensor” and “viewer” will be used interchangeably here to mean any person or device that is receiving an image, including when said image is a laser dot.
A common problem with both telescopic viewing and laser targeting is that angular error introduced by movements of the person, object or vehicle holding the viewing device or laser pointer is amplified by the distance between the device and the target. Relatively small angular movements in any direction are increased proportional to the distance between the observer and the target. In the case of scopes, the result is a loss of visual acuity and clarity. The image viewed is so shaky and blurred relative to the original image that the viewer cannot perceive the image in the detail desired. The amplification of these angular movements over several miles can result in an image that is so shaky and blurred that the image is completely obscured. In the case of targeting, the result is a target “dot” that jumps around by as much as several meters, even jumping off target entirely, and failing to provide a stable and reliable guide for the projectile. Clearly, the ramifications of this error are tremendous; one would expect a laser guided projectile to adequately locate its target, but with such an unstable laser dot, such accuracy is impossible. As such, there is a great need in the art for a means to stabilize the viewing or pointing device, thus increasing the accuracy of lasers and the clarity of telescopic images.
The current practice is to refract the light rays (whether from the image or the laser) through a glass prism mounted within a bi-directional gimbal system that stabilizes the prism in two directions perpendicular to one another across the optical axis of the device. See U.S. Pat. No. 4,465,346 and U.S. Pat. No. 4,318,584. In some cases, the gimbal is further stabilized by a gyroscope. This practice is insufficient for resolving the problems stated above, as said practice requires bulky and inconvenient materials, while still failing to provide the clarity and image strength desired. Specifically, the use of glass prisms and the gimbals that are standardly employed are somewhat effective but fail to adequately solve the problems in the field.
In particular, glass prisms are wavelength-specific, meaning use of different lasers (red vs. green vs. infrared, for example) requires a different prism for each laser wavelength. This is especially problematic in that glass prisms are comparatively heavy and add undesired weight to the device. Additionally, as glass is by nature fragile, a prism is susceptible to chipping or breaking. Moreover, glass prisms absorb some light, meaning less light reaches the observer or the target, resulting in a weaker “dot” signal or image.
Most systems in current use have gimbals with servo motors and motion detection to feedback to the motors, creating a “reactive” system that stabilizes the gimbal. The system will naturally deviate through the angular motion referred to before or through an alternative source of motion; the deviation is then detected; and finally the motion is corrected via servo motors. Such systems are bulky and, while they may decrease the angular motion somewhat by reacting and correcting it via the servo motions, they are imperfect in that they do not prevent the angular motion amplification, resulting in a similar loss of accuracy. Moreover, the greater the weight of the gimbal and optics within the gimbal, the greater the load on the motors, which ultimately impacts the weight and energy usage of the system.
Therefore, there is a need for an apparatus or system that is comparatively lightweight, is useful at all wavelengths, results in increased clarity, and provides a strong signal.